Calculation Of Interdiffusivity Of Fe And Al In Aluminide Coating Arc-sprayed On Mild Steel

With the development of the modern industry, the material protection is gradually got theattention. Now in order to protect the material in the work and prolong the useful life of thematerial, the most effective method is to use coating on the surface of the material. Andelectric arc spraying is one of the most excellent method of preparing coating. Compared withother methods, it has many good characteristics, such as low cost, high efficiency, goodsecurity, act. Now more and more people adopt the method of electric arc spraying to sprayaluminide coating on the surface of the material in order to achieve the best protecting effect.The particular protecting characteristic of the aluminide coating has been accepted by thepublic. The aluminium oxide film which is produced by the aluminide coating can prevent thematerial from the high temperature oxidation erosion, and also successfully prevent it fromeroding more. So it improves the useful life of the material.The diffusion depth of aluminium determines the protecting ability to the material andthe useful life of the coating. If the diffusion depth is deeper, the protecting ability of thecoating is better, and its useful life is longer. The diffusion depth of the aluminium atom inthe body depends on the diffusion coefficient. So the research on the diffusion coefficient isvery important.This topic mainly researches the diffusion coefficient of iron-aluminium. Al coatingswere sprayed on the substrate of Q235-A steel by arc spraying, the microstructure of iron alcoatings is investigated by transmission electron microscope (TEM), scanning electronmicroscope (SEM), X-ray analysis (XRD) and energy dispersive spectrometer(EDS). Theformation mechanism of iron al intermetallic composite discussed and diffusion mechanismof composite coatings studied under specific temperature in this paper.The finite difference method equation that was based on some postulations wasintroduced to calculate the interdiffusivity in the aluminide coatings formed on Q235-A steel.The calculation is based of the Al weight fraction in aluminide coatings formed on Q235-Asteel. The calculating results indicated that the interdiffusivity increased with increasing Alcontent and that the interdiffusivity ranged among 10^-12～10^-11at 800℃and that at 900℃was among 10¹¹ï½ž101^-10. Those revealed that the interdiffusivity was greatly affected by Al weightfraction in the aluminide coating and diffusing temperatures provide the theoretical basis forthe application and production of iron aluminide intermetallic coatings.